A retarder auxiliary engine brake system provides alternative breaking capacity for heavy duty vehicles when needed. Engine brake systems can apply extended light breaking action with no break fade, thereby controlling the vehicles downgrade speed to save the vehicle service breaks until they are needed.
A portion of an exemplary engine brake system 10 is shown in FIG. 1. The exemplary system is an MX-11 engine brake system; however, it should be appreciated that aspects of the present disclosure generally apply for any suitable engine brake system. The engine brake system 10 includes a solenoid valve 14 secured within a solenoid mounting portion 12 having an oil inlet line 16 and an oil outlet line 20. In that regard, the solenoid valve 14 includes and inlet opening 24 at a bottom end of the valve that is in fluid communication with the oil inlet line 16, and an outlet opening 28 near a middle portion of the valve that is in fluid communication with the oil outlet line 20. The solenoid valve 14, when activated, allows pressurized engine oil to flow from the oil inlet line 16 to the oil outlet line 20 and thereafter to a control valve 18, such as a one-way check valve.
The pressurized engine oil passes through the control valve 18 to extend a slave piston 22 to initiate the engine braking function. Upon pressure from the oil, the slave piston 22 extends and pushes down on an exhaust valve 26. The control valve 18 prevents oil from backing out of the system, i.e., the control valve 18 traps oil in the slave piston 22 to maintain it in an extended state.
During operation, a master piston (not shown) positioned axially beneath the exhaust valve 26 moves between first and second positions in sync with the movement of the slave piston 22 and exhaust valve 26. In other words, as the slave piston 22 and exhaust valve 26 extend, the master piston retracts, and vice versa. Sufficient clearance exists such that when the slave piston 22 and master piston are in sync, the exhaust valve 26 does not interfere with the master piston. If the exhaust valve 26 hits the master piston, severe engine damage could occur. Accordingly, it can be appreciated that if the slave piston 22 is not functioning properly, the exhaust valve 26 could hit or interfere with the master piston.
The slave piston 22 may function sub-optimally if the engine oil is not replaced as needed or other misuse occurs. In such suboptimal conditions, the slave piston 22 may wear, bind, etc., causing the slave piston 22 to either stick during the extension and retraction phases, or not fully extend or retract. Full extension of the slave piston 22 has a direct correlation with engine brake effectiveness. Moreover, stiction in at least one of the extension and retraction phases may cause lower power and may even destroy the engine if the exhaust valve 26 clashes with the master piston.
Thus, there is a need for a system or method for testing the actuation of the slave piston 22 to assess the health of the engine brake system. Testing the movement of the slave piston 22 during engine operation is impractical, since the high pressure oil is flowing through the system. Moreover, a separate test fixture (replicating the brake system) would be costly and cumbersome. The engine brake test tool 10 of the present disclosure allows the functionality of the slave piston 22 to be tested in a simple, inexpensive, safe manner.